Intravascular systems for corporeal cooling

ABSTRACT

A catheter for intravascular corporeal cooling comprises an elongated tubular member having at least one lumen extending therethrough for providing cooled blood, an inflatable annular balloon positioned on the outer surface of the elongated tubular member, and a pressure reliever positioned in the external wall of the elongated tubular member and proximal to the annular inflatable balloon, wherein when the pressure of blood within a lumen reaches a predetermined value, the pressure reliever opens to permit fluid to be released from the elongated tubular member. In other embodiments of the invention the catheter may have two or more inflatable annular balloons that are separately inflatable and/or the catheter has an insulative outer annular member.

FIELD OF THE INVENTION

This invention is directed to intravascular systems for corporealcooling. More particularly, this invention is directed to cathetersystems that have features that are especially useful for coolingorgans, tissue, or limbs.

BACKGROUND OF THE INVENTION

It has been found that cooling of the central nervous system providesmany advantages in dealing with neurological problems. Beneficialresults have been obtained from hypothermia of the intracranialstructures in surgical treatment of certain brain tumors,cerebrovascular lesions such as aneurysms and hemangiomas, and headinjuries. Hypothermia of the intracranial structures results in adecrease in brain volume and cerebral blood flow, as well as the arrestof cerebral edema when present. Furthermore, when the tissue of thecentral nervous system cools, there is a decrease in oxygen consumptionand, therefore, greater protection against anoxia during deficient orarrested circulation. In addition, the resistance of brain tissue tosurgical trauma is markedly increased and surgical bleeding is easy tocontrol. Thus, local or regional hypothermia of the central nervoussystem is effective as a therapeutic technique, per se, as a surgicalaid and also as a post-operative technique.

Cerebral hypothermia in the past has been brought about by cooling theentire body (surface cooling and intravascular perfusion), cooling thevascular supply to the brain, regional hypothermia by extracorporealintravascular perfusion, or by the use of cold capsules or ice applieddirectly to the cerebral hemispheres. Systemic hypothermia byintravascular perfusion requires an additional major surgical procedureand carries with it a number of complications. A serious complicationsometimes experienced through the use of systemic hypothermia (surfaceor intravascular) is ventricular fibrillation and cardiac asystole,which is attributable to the lower temperature tolerance of heartneuromuscular elements, as compared with central nervous system tissue.

There are a number of intravascular systems that are presently used forcorporeal cooling, especially brain cooling. However, it has been foundthat there are certain disadvantages when such systems are used, andthere is a definite need for improved systems.

OBJECTS OF THE INVENTION

It is an object of the invention to provide intravascular systems usefulfor corporeal cooling, especially cooling the brain or other organs,such as the kidneys.

It is also an object of the invention to provide an intravascuar systemfor corporeal cooling that has a pressure dependent valve.

It is a further object of the invention to provide a method for treatingstroke patients where the patients are treated by brain cooling shortlyafter the stroke event to minimize insult and/or damage.

It is yet a further object of the invention to provide an intravascularsystem having balloons with variable inflation.

It is an additional object of the invention to provide an insulatedintravascular system.

It is a still further object of the invention to provide anintravascular system having variable fenestration.

It is likewise an object of the invention to provide an intravascularsystem for cooling organs, tissue, or limbs.

It is a yet further object of the invention to provide an intravascularsystem for delivering drugs or other fluids to a desired corporeallocation.

These and other objects of the invention will become more apparent fromthe discussion below.

SUMMARY OF THE INVENTION

In an intravascular brain cooling procedure, a catheter is advanced intothe common carotid artery and the distal tip of the catheter ispositioned within the internal carotid artery. Preferably the distal tipof the catheter has one or more inflatable balloons or other structuresto obstruct the annular space between the outer surface of the catheterand the inner surface of the internal carotid artery. Cooled blood isprovided to the brain through one or more lumens in the catheter.

A catheter for corporeal cooling may have a pressure sensitive valve toprovide relief in the event of pressure build-up within the catheter.Also, the catheter may be insulated to avoid systemic cooling andrelated cardiac complications. At the proximal section of a corporealcooling catheter system where the patient's blood is removed forcooling, an outer catheter sheath may comprise variable fenestrations tofacilitate blood withdrawal. Optionally a catheter according to theinvention may have one or more pressure sensors to sense blood pressurewithin or without the catheter.

In addition, it has been found that brain cooling may be beneficial whenapplied to stroke patients. Further, cooling a kidney by providingcooled blood into a renal artery can be effective in treating renalfailure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an embodiment of the inventionhaving a pressure-dependent valve;

FIG. 2 is a schematic representation of an embodiment of the inventionhaving variable inflation;

FIG. 3 is a partially cross-sectional view of an embodiment of theinvention wherein the intravascular system is insulated;

FIG. 4 is an oblique view of one end of the intravascular system shownin FIG. 3;

FIG. 5 is a partially cross-sectional view of an embodiment of theinvention wherein intravascular system is partly insulated;

FIGS. 6 and 7 are each a partially cross-sectional view of a portion ofan insulated intravascular catheter;

FIG. 8 is a partially cross-sectional view of another embodiment of aninsulated intravascular system according to the invention;

FIG. 9 is a partly cross-sectional view of another embodiment of theinvention; and

FIG. 10 is an oblique, schematic view of an embodiment of the inventionhaving fenestrations.

DETAILED DESCRIPTION OF THE INVENTION

The invention herein can perhaps best be appreciated from the drawings.In FIG. 1, the distal end 10 of an intravascular corporeal catheter 12is positioned within the internal carotid artery 14. Distal end 10comprises at least one inflatable balloon 16 to seal the annular space18 between the outer surface 20 of catheter 12 and the inner surface 22of internal carotid artery 14.

Catheter 12 comprises two or more lumens, at least an inflation lumen 24for inflation of balloon 16 and a lumen 26 for providing cooled blood inthe direction of arrow 28. Proximal to distal end 10 and preferablywithin common carotid artery 30 is a pressure-dependent valve or reliefmeans 32. Valve 32, which is intended to be in the wall of, or otherwisein fluid communication with, lumen 26, is intended to rupture in theevent the pressure of blood within lumen 26 exceeds a pre-determinedvalue, to avoid any problem associated with supplying blood under toomuch pressure to the brain.

Valve 32 can be comprised of any of several known one-way valving means,which include, for example, slits, fissures, caps, flaps, friablemembranes, and the like.

The intravascular corporeal catheter 40 shown in FIG. 2 comprises adistal section 42 positioned within internal carotid artery 44. Distalsection 42 comprises two or more, preferably 3 or 4, inflatable balloons46 positioned in the annular space 48 between the outer surface 50 ofcatheter 40 and the inner surface 52 of internal carotid artery 44.Preferably each balloon 46 has a separate inflation lumen 54 extendingin the proximal direction to an inflator (not shown). However, it iswithin the scope of the invention that two or more, adjacent ornon-adjacent, balloons could be in fluid communication with a singleinflation lumen. The inflator is capable of inflating balloons 46 in adesired sequence and/or pressure to obstruct flow within annular space48. An example of inflator technology useful according to the inventionis described in U.S. Pat. No. 3,931,822, incorporated herein byreference.

Catheter 40 also comprises at least one lumen 56 to provide cooled bloodto the brain in the direction of arrow 58.

FIG. 3 is a cross-sectional view of a portion of a catheter 60especially useful for intravascular corporeal cooling. Catheter 60comprises an outer cylindrical wall 62 and an inner cylindrical wall 64,which inner wall preferably comprises at least one lumen 66 forproviding cooled blood. The annular or substantially annular space 68between inner wall 64 and outer wall 62 should provide insulativeproperties. For example, the annular space may comprise a fluid,preferably a gaseous fluid such as air, or other insulation materialsuch as any of the known synthetic insulation materials, silica gel, orthermal insulating materials such as are disclosed in U.S. Pat. Nos.2,967,152, 3,007,596, and 3,009,600, all of which are incorporatedherein by reference. The insulation used should not restrict, or shouldhave only minimal impact upon, the flexibility of catheter 60.

A schematic, oblique cross-section of catheter 60 is shown in FIG. 4.Annular space 68 between outer wall 62 and inner wall 64 can be filledwith fluid or insulation.

The insulation construction described may extend for the entire lengthor for only a portion of an intravascular corporeal catheter. Forexample, as shown in FIG. 5, the annular space 68 may terminate atsurface 70 and inner wall 64 will continue as an uninsulated catheter.Also, as shown in FIGS. 6 and 7, either or both of the proximal anddistal ends, especially the distal end, of catheter 60, then the annularspace 68 may taper to a distal point 72 of catheter 60.

According to the embodiment of the invention shown in FIG. 8, anintravascular corporeal catheter 80 comprises a longitudinal tubularmember 82 that has a partially co-extensively extending inflatableinsulation member 84. Insulation member 84 is sealed to the extension oftubular member 82 at distal position 86 and proximal position 88, theinterior 90 of inflatable insulation member 84 being in fluid connectionthrough inflation lumen 92 with an inflator (not shown). Inflationmember 84 is intended to have a low profile and facilitate insertionthrough the femoral artery 94 into the aorta 96, which is larger indiameter. Once inflation member 84 is positioned within aorta 96,inflation member 84 is inflated to provide insulation when cooled bloodis passed through one or more lumens 98 in catheter 82 in the directionof arrow 100.

Intravascular corporeal catheters 12, 40, 60, and 80 as shown in FIGS. 1to 8 are especially useful in brain cooling, where cooled blood isprovided to a patient's brain. However, it is within the scope of theinvention that each of said catheters may have broader use in coolingother organs, tissue, or limbs, or even in the delivery of substancessuch as pharmaceuticals or other agents to desired sites within apatient's body.

FIG. 9 is a schematic representation of an embodiment of the inventionparticularly useful when the internal carotid artery 134 has plaque 122.A catheter 124 comprises a through lumen 126 for passage of a guidewire(not shown) and optionally blood for the external carotid artery.Catheter 124 also comprises at least one blood flow lumen 128 having aclosed distal end 130 and a lateral opening 132 for providing cooledblood to the internal carotid artery 134. Inflatable balloons 136, 138are positioned in the external carotid artery 120 and the common carotidartery 140, respectively. Cooled blood flows in the direction of arrow142 through lateral opening 132 and within plaque 122 into internalcarotid artery 134.

It is within the scope of the invention that a corporeal coolingcatheter could have additional capability, such as pressure and/ortemperature measurement. For example, in FIG. 1 catheter 12 may comprisea lumen 34 having a distal end 36. Distal end 36 could be open oroptionally it could comprise an element 38 which is a transducer ordiaphragm, optionally with fiber optic cable 160. A number of knowntechniques for measuring pressure and/or temperature can be used,including, but not limited to, a configuration where there is no lumen34 and a transducer element 38 could be electrically connected via wires(not shown) to a controller (not shown). Also, there could be more thenone pressure and/or temperature sensor, located at different positionson the distal section of a corporeal cooling catheter. For example, inFIG. 1, a pressure sensor element 38 could be located where shown or onthe surface of catheter 10 distal or proximal to balloon 16. Forrepresentative examples of pressure and/or temperature sensortechnology, see, for example, U.S. Pat. Nos. 4,487,206, 4,641,654,5,427,114, 5,456,251, 5,325,865, 5,647,847, 5,866,821, and 5,899,927,all of which are incorporated herein by reference. Measurement ofpressure is of particular interest. Flow and pressure greater than thedesired range may lead to brain injury, and flow and pressure less thanthe desired range may be insufficient to achieve organ cooling.

As part of the brain cooling process blood has to be removed from thepatient for cooling and then returned to the patient. Preferably thiscan be done in a single site to minimize trauma to the patient. It isknown to use a catheter set wherein an outer catheter extends onlyshortly distally into the patient's artery, blood is removed proximallythrough an annular space between the outer catheter and adistally-extending inner catheter, and cooled blood is returned throughthe inner catheter. However, since the available surface area forproximal blood flow is only a profile corresponding to said annularspace, there are sometimes problems that develop due to pressure orfluid build-up in this area. According to an embodiment of theinvention, and as shown in FIG. 10, the distal end 150 of an introducersheath 152 contains fenestrations 154 of varied, uniform, or variablesize. Cooled blood is returned in the direction represented by arrow 156through catheter 158. Body temperature blood enters introducer sheath152 in the direction of the arrows at distal end 150 throughfenestrations 154. Fenestrations 154 preferably are circular,substantially circular, or oval, and have a diameter or effectivediameter of from about 0.5 to 5 mm. It is within the scope of theinvention that introducer sheath 152 comprise two concentric, slidablyand/or rotably arranged tubular members so that the member and/or sizeof the fenestrations can be varied by rotating or sliding the outer ofthe two concentric members.

Another aspect of the invention concerns the use of brain cooling totreat stroke victims. When the cerebral vasculature of a stroke victimis flushed with cooled blood, the insult or damage normally associatedwith a stroke is either minimized or avoided altogether. Theeffectiveness of the brain cooling will depend upon several factors,including the severity of the stroke, the length of time after thestroke that the patient is treated, the duration of the treatment, thetemperature of the cooled blood, the volume of cooled bloodadministered, etc. For example, the duration of the treatment could befrom about 6 to 18 hours, the temperature of the cooled blood could befrom about 16° to 24° C., and the volume of the cooled blood could befrom about 100 to 900 ml/min. It is significant that the flow rateand/or pressure of the cooled blood should be adjusted so that the bloodpressure in the stroke patient's internal carotid artery is slightlygreater than systemic blood pressure.

It would be advantageous to treat a stroke victim as soon as possibleafter the stroke, it being understood that the treatment is likely to bemost effective if the patent is treated within 12 hours after thestroke. It is preferred that brain cooling be administered no more than12 hours after the stroke, although treatment up to 18 hours or evenmore may still be of limited effectiveness, dependent upon all thefactors involved.

In a preferred embodiment of the invention the brain cooling isadministered in conjunction with a thrombolytic agent such as TPA,heparin, streptokinase, or the like. The thrombolytic agent could beadministered according to known protocols prior to, during, and/orsubsequent to the brain cooling. Similarly, in the event that surgicalor endovascular intervention is indicated in a stroke victim, braincooling could be administered in conjunction with such a procedure.

To effect vascular brain cooling according to the invention, normalprocedures are followed. First, a guide catheter is established and thenthe distal tip of a brain cooling catheter is advanced through thefemoral artery, through the aorta, into the common carotid artery. Then,dependent upon which embodiment of the invention described herein isemployed, the distal tip of the brain cooling catheter is thenpositioned in either the internal carotid or the external carotidartery, whereupon the inflation balloons are inflated. Cooled blood isperfused through one or more lumens in the brain cooling catheter to theinternal carotid artery.

According to one embodiment of the invention, cooled blood is providedto one or more kidneys to treat, minimize, or avoid renal failure. Acatheter according to the invention, preferably a catheter such asdescribed in FIG. 1, is advanced through the aorta and then into theleft or right renal artery. The distal tip of the catheter is thenpositioned in the left or right renal artery at a point between theaorta and the left or right kidney, respectively. Once the annularballoon is inflated, cooled blood perfuses the kidney. While preferablyone kidney is treated at a time, possibly sequentially, it is within thescope of the invention that both kidneys could be treatedsimultaneously, dependent upon the equipment used. The conditions oftreatment in terms of blood temperature, blood flow, and duration wouldbe similar to those for brain cooling, with the exception that suchrenal treatment is likely to be of less duration.

Any of the known devices for cooling blood during cardiac procedurescould be used. One example of such available equipment to cool thepatient's blood is the SARNS TCM water bath available from the SARNSCorp. of Ann Arbor, Mich. Such a water bath is used with acardiopulmonary bypass machine such as the BP40, available fromBiomedicus, Minneapolis, Minn. Details regarding brain coolingprocedures are readily available See, for example, A. E. Schwartz etal., “Isolated Cerebral Hypothermia by Single Carotid Artery perfusionof Extracorporeally Cooled Blood in Baboons”, Neurosurgery, Vol. 39, No.3, September 1996, pp. 577-582, and A. E. Schwartz et al., “SelectiveCerebral Hypothermia by Means of transfemoral Internal Carotid ArteryCatherization”, Radiology, Vol. 201, No. 2, November 1996, pp. 571-572,both of which are incorporated herein by reference.

The catheters described above comprise conventional bio-compatiblematerials used in the catheter field. For example, the catheters may becomprised of suitable low-friction bio-compatible polymers such as, forexample, extruded polyethylene polyvinyl chloride, polystyrene, orpolypropylene or copolymers thereof. Inflatable balloons would becomprised of polymers or polypropylenes or copolymers thereof. Thecatheters may have a hardness of, for example, from 60 to 90 Shore Aduramter. The inner elongated tubular members of the invention wouldtypically have an i.d. of from about 7.5 to 10.5 F and an o.d. of fromabout 8 to 11 F, where an outer tubular member would typically have ani.d. of from about 8.5 to 11.5 F and an o.d. of from about 9 to 12 F.

The catheters useful according to the invention may optionally have oneor more radiopaque markers in their distal sections, the markerspreferably comprising rings comprised of tantalum, platinum, or gold.Also, the catheter may have any of the well-known anti-thrombotic orlubricious coatings.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, however, that other expedientsknown to those skilled in the art or disclosed herein, may be employedwithout departing from the spirit of the invention or the scope of theappended claims.

What is claimed is:
 1. A catheter for intravascular corporeal cooling which comprises: an elongated tubular member having proximal and distal sections, at least first and second lumens extending therethrough, an outer surface, and an outer wall, an inflatable annular balloon positioned on the outer surface of the elongated tubular member and in fluid communication with a lumen for inflation, and pressure relief means positioned in the outer wall of the elongated tubular member and proximal to the annular inflatable balloon, wherein at least the first lumen can provide cooled blood in the distal direction and distal to the inflatable annular balloon, and when the pressure of fluid within the first lumen reaches a predetermined value, the pressure relief means opens to permit fluid to be released from the elongated tubular member.
 2. The catheter of claim 1, wherein the annular balloon is in fluid communication with an inflation lumen extending longitudinally through the tubular member.
 3. The catheter of claim 1, which comprises at least one additional inflatable annular balloon.
 4. The catheter of claim 3, wherein each inflatable annular balloon is in fluid communication with an inflation lumen.
 5. The catheter of claim 1 which also comprises a pressure sensor at or adjacent to the distal end of the catheter.
 6. The catheter of claim 1 which has been adapted for brain cooling.
 7. The catheter of claim 1, wherein at least one lumen is in fluid communication with a source of cooled blood.
 8. The catheter of claim 1, wherein at least one lumen is in fluid communication with a liquid pharmaceutical source.
 9. A catheter for intravascular corporeal cooling which comprises: an elongated tubular member having proximal and distal sections, at least first and second lumens extending therethrough, an outer surface, and an outer wall; an inflatable annular balloon positioned on the outer surface of the elongated tubular member and in fluid communication wit a lumen for inflation; and pressure relief means comprising a one-way valve positioned in the outer wall of the elongated tubular member and proximal to the annular inflatable balloon, wherein at least the first lumen can provide cooled blood in the distal direction and distal to the inflatable annular balloon, and wherein when the pressure of fluid within the first lumen reaches a predetermined value, the pressure relief means opens to permit fluid to be released from the elongated tubular member.
 10. The catheter of claim 9, wherein the annular balloon is in fluid communication with an inflation lumen extending longitudinally through the elongated tubular member.
 11. The catheter of claim 9, which comprises at least one additional inflatable annular balloon.
 12. The catheter of claim 11, wherein each inflatable annular balloon is in fluid communication with an inflation lumen.
 13. The catheter of claim 9 which also comprises a pressure sensor at or adjacent to the distal end of the elongated tubular member.
 14. The catheter of claim 9 which is useful for brain cooling.
 15. The catheter of claim 9, wherein at least one lumen is in fluid communication with a source of cooled blood.
 16. The catheter of claim 9, wherein at least one lumen is in fluid communication with a liquid pharmaceutical source.
 17. A catheter for intravascular corporeal cooling which comprises: an elongated tubular member having proximal and distal sections, at least first and second lumens extending therethrough, an outer surface, and an outer wall; an inflatable annular balloon positioned on the outer surface of the elongated tubular member and in fluid communication with a lumen for inflation; pressure relief means positioned in the outer wall of the elongated tubular member and proximal to the annular inflatable balloon, and a pressure sensor at or adjacent to the distal end of the elongated tubular member, wherein at least the first lumen can provide cooled blood in the distal direction and distal to the inflatable annular balloon, and wherein when the pressure relief means opens to permit to be released from the elongated tubular member.
 18. The catheter of claim 17, wherein the pressure relief means comprises an elongated fissure.
 19. The catheter of claim 17, wherein the annular balloon is in fluid communication with an inflation lumen extending longitudinally through the elongated tubular member.
 20. The catheter of claim 17, which comprises at least one additional inflatable annular balloon.
 21. The catheter of claim 20, wherein each inflatable annular balloon is in fluid communication with an inflation lumen.
 22. The catheter of claim 17 which is useful for brain cooling.
 23. The catheter of claim 17, wherein at least one lumen is in fluid communication with a source of cooled blood.
 24. The catheter of claim 17, wherein at least one lumen is in fluid communication with a liquid pharmaceutical source.
 25. A catheter for intravascular corporeal cooling which comprises: an elongated tubular member having proximal and distal sections, at least first and second lumens extending therethough, an outer surface, and an outer wall; an inflatable annular balloon positioned on the outer surface of the elongated tubular member and in fluid communication with a lumen for inflation; and pressure relief positioned in the outer wall of the elongated tubular member and proximal to the annular inflatable balloon, wherein at least the first lumen can provide cooled blood in the distal direction and distal to the inflatable annular balloon, wherein at least one lumen is in fluid communication with a source of cooled blood, and wherein when the pressure of fluid within the first lumen reaches a predetermined value, the pressure relief means opens to permit fluid to be released from the elongated tubular member.
 26. The catheter of claim 25, wherein the pressure relief means comprises an elongated fissure.
 27. The catheter of claim 25, wherein the annular balloon is in fluid communication with an inflation lumen extending longitudinally through the elongated tubular member.
 28. The catheter of claim 25, which comprises at least one additional inflatable annular balloon.
 29. The catheter of claim 28, wherein each inflatable annular balloon is in fluid communication with an inflation lumen.
 30. The catheter of claim 25 which is useful for brain cooling.
 31. The catheter of claim 25, wherein at least one lumen is in fluid communication with a liquid pharmaceutical source.
 32. A catheter for intravascular coporeal cooling which comprises: an elongated tubular member having proximal and distal sections, at least first and second lumens extending therethrough, an outer surface, and an outer wall; an inflatable annular balloon positioned on the outer surface of the elongated tubular member and in fluid communication with a lumen for inflation; and pressure relief means positioned in the outer wall of the elongated tubular member and proximal to the annular inflatable balloon, wherein at least the first lumen can provide cooled blood in the distal direction and distal to the inflatable annular balloon, wherein at least one lumen is in fluid communication with a liquid pharmaceutical source, and wherein when the pressure of fluid within the first lumen reaches a predetermined value, the pressure relief means opens to permit fluid to be released from the elongated tubular member.
 33. The catheter of claim 32, wherein the pressure relief means comprises an elongated fissure.
 34. The catheter of claim 32, wherein the annular balloon is in fluid communication with an inflation lumen extending longitudinally through the elongated tubular member.
 35. The catheter of claim 32, which comprises at least one additional inflatable annular balloon.
 36. The catheter of claim 35, wherein each inflatable annular balloon is in fluid communication with an inflation lumen.
 37. The catheter of claim 32 which is useful for brain cooling. 